Hard gelatin capsules were traditionally a popular dosage form for prescription and over-the-counter (OTC) drugs, and many patients preferred capsules over tablets, perceiving them as being easier to swallow. An alternative to capsule products are caplets, which are solid, oblong tablets that are often coated with various polymers such as cellulose ethers to improve their aesthetics, stability, and swallowability. Typically, such polymers are applied to the tablets either from a solution in organic solvents, or from an aqueous solution or dispersion via spraying. However, such spray-coated tablets lack the shiny surface and elegance of the hard gelatin capsules. Additionally, it is not commercially feasible to spray-coat a caplet with a different color coating on each end.
Another alternative to capsule products are gelcaps, which are elegant, shiny, consumer-preferred dosage forms that are prepared by dipping each half of an elongated tablet into two different colors of gelatin solution. See U.S. Pat. Nos. 4,820,524; 5,538,125; 5,770,225; 5,198,227; and 5,296,233, which are all incorporated by reference herein. A similar dosage form, commercially available as a “geltab,” is prepared by dipping each half of a round, convex tablet into different colors of gelatin solution, as described in U.S. Pat. Nos. 5,228,916, 5,436,026 and 5,679,406, which are all incorporated by reference herein.
However, the use of gelatin as a pharmaceutical coating material presents certain disadvantages and limitations, including the potential for a decrease in the dissolution rate after extended storage, due to the cross-linking of the gelatin, and potential for microbial contamination of the gelatin solution during processing.
It is desirable to find a dip coating material, which not only produces a similar elegant, shiny, high gloss, consumer-preferred dosage form similar to that of gelatin-coated forms, but which is absent the limitations of gelatin, particularly those noted above.